The various embodiments described herein include methods, devices, and systems for fabricating and operating niobium-germanium-based superconducting devices. In one aspect, a device includes a superconducting nanowire composed of niobium-germanium, a protective layer configured to inhibit oxidation of the superconducting nanowire, and a current source configured to supply a current to the superconducting nanowire. In another aspect, a method of fabrication includes: (1) depositing a layer of niobium-germanium on a substrate; (2) removing one or more portions of the layer of niobium-germanium to define one or more nanowires; and (3) depositing a protective layer over the one or more nanowires, the protective layer adapted to inhibit oxidation of niobium-germanium in the one or more nanowires.

In various embodiments, superconducting wires feature assemblies of clad composite filaments and/or stabilized composite filaments embedded within a wire matrix. The wires may include one or more stabilizing elements for improved mechanical properties.

The various embodiments described herein include methods, devices, and systems for fabricating and operating niobium-germanium-based superconducting devices. In one aspect, a device includes a superconducting nanowire composed of niobium-germanium, a protective layer configured to inhibit oxidation of the superconducting nanowire, and a current source configured to supply a current to the superconducting nanowire. In another aspect, a method of fabrication includes: (1) depositing a layer of niobium-germanium on a substrate; (2) removing one or more portions of the layer of niobium-germanium to define one or more nanowires; and (3) depositing a protective layer over the one or more nanowires, the protective layer adapted to inhibit oxidation of niobium-germanium in the one or more nanowires.

In various embodiments, superconducting wires incorporate diffusion barriers composed of Ta alloys that resist internal diffusion and provide superior mechanical strength to the wires.

In various embodiments, superconducting wires incorporate diffusion barriers composed of Ta alloys that resist internal diffusion and provide superior mechanical strength to the wires.

A precursor, which is a drawn wire product of a composite pipe, the composite pipe having: a composite wire group; a barrier layer; and a protective layer, wherein the composite wire group has: a plurality of tin wires each having at least one tin core being made of tin or a tin alloy, and a copper matrix which surrounds the at least one tin core; and a plurality of niobium wires each having a plurality of niobium cores being made of niobium or a niobium alloy, and a copper matrix which surrounds the plurality of niobium cores, the plurality of niobium wires being disposed such that each of the tin wires is surrounded by the niobium wires, the composite wire group contains titanium in an amount of from 0.38% by mass to 0.55% by mass.

Methods of forming semiconductor-superconductor hybrid devices with a horizontally-confined channel are described. An example method includes forming a first isolated semiconductor heterostructure and a second isolated semiconductor heterostructure. The method further includes forming a left gate adjacent to a first side of each of the first isolated semiconductor heterostructure and the second isolated semiconductor heterostructure. The method further includes forming a right gate adjacent to a second side, opposite to the first side, of each of the first isolated semiconductor heterostructure and the second isolated semiconductor heterostructure, where a top surface of each of the left gate and the right gate is offset vertically from a selected surface of each of the first isolated semiconductor heterostructure and the second isolated semiconductor heterostructure by a predetermined offset amount. The method further includes forming a superconducting layer over each of the first isolated semiconductor heterostructure and the second isolated semiconductor heterostructure.

A vertical q-capacitor includes a trench in a substrate through a layer of superconducting material. A superconductor is deposited in the trench forming a first film on a first surface, a second film on a second surface, and a third film of the superconductor on a third surface of the trench. The first and second surfaces are substantially parallel, and the third surface in the trench separates the first and second surfaces. A dielectric is exposed below the third film by etching. A first coupling is formed between the first film and a first contact, and a second coupling is formed between the second film and a second contact in a superconducting quantum logic circuit. The first and second couplings cause the first and second films to operate as the vertical q-capacitor that maintains integrity of data in the superconducting quantum logic circuit within a threshold level.

In various embodiments, superconducting wires feature assemblies of clad composite filaments and/or stabilized composite filaments embedded within a wire matrix. The wires may include one or more stabilizing elements for improved mechanical properties.

A new heat treatment for Internal-Tin Nb.sub.3Sn strands is described. The heat treatment uses Nausite membranes to decrease the volume fraction of the phase and therefore minimize its liquefactionultimately resulting in better connected Nb.sub.3Sn. The heat treatment requires only one stage aside from the final Nb.sub.3Sn reaction stage. This heat treatment enables an increase in critical current density (at 16 T) of 28%.